What does it mean to open a field and guard the border?

The meaning of stationing troops and guarding the border is an important measure for China's border defense. Reclaiming farmland refers to the abandoned fields reclaimed by soldiers and farmers for military supplies or grain requisition since the Han Dynasty. In the past dynasties, there were military camps, civilian camps and commercial camps.

Emperor Wu of the Han Dynasty reclaimed land in the western regions, and when Han announced that he would reclaim land in border counties, he used the garrison as his army. During the Three Kingdoms period, Cao Cao made a promise of land reclamation, and began to cultivate the people by farming officials, which was called people's land shortage. The farmer who wants to recruit is called a farmer, asking officials to give cows and seeds, and rewarding six officials and four. If farmers bring their own cattle, they will get half a point; It was not until the Ming Dynasty that there was a Shang Tun.

In the middle of the Ming dynasty, salt merchants raised people in the frontier to open up wasteland and farm, and exchanged grain and grass for salt, which was called Shangtun. Because of its strong organization and large cultivated land area, it can adopt advanced farming methods, so the output is generally high, so it can accumulate a large amount of grain in a period of time, thus enhancing the country's strength.